1. Field of the Invention
The invention relates to a method for determining at least one characteristic of an antenna and an advantageous measuring device for this purpose.
2. Description of Related Art
A characteristic of an antenna is understood to mean any kind of characteristic of the antenna, for example individual parameters, time curves of parameters or direction—and frequency-dependent characteristics, for example radiation diagrams. With known methods, such characteristic data of antennas are usually determined within the frequency domain. A test signal is thereby generated by a frequency generator, such that a so-called frequency sweep is performed over a particular frequency range which is to be examined. Each frequency is thereby held constant for a short period of time, until the antenna achieves a steady-state condition. A measurement is then carried out on the antenna in order to determine the characteristic data.
One known method is, for example, the reference antenna method, which requires an absolutely defined radiating antenna, for example an open waveguide probe or a horn antenna, as reference. A disadvantage of this method is that measuring is relatively time-consuming and/or costly, since several reference antennas often need to be provided and measured in succession, as such reference antennas display a limited, relatively narrow effective bandwidth. In order also to provide a high purity of polarization, precisely manufactured and absolutely characterized reference antennas are necessary, which are therefore relatively expensive. In many cases, therefore, such expenditure is not justified. Also known is the 2-antenna method, in which two antennas of exactly identical design must be placed opposite one another at a defined distance in a reflection-free space. This method gives rise to the problem of obtaining two antennas of exactly identical design, which can be difficult in individual cases. Also known is the 3-antenna method which, while delivering good results, is relatively time-consuming and labor-intensive.